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TR6 When does your TR6 run out of breath?
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BobbyD
Jedi Knight
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Interesting question.......over in 6-pack there's a bunch of dyno results posted that will show both stock and modified engines.
In stock form I could never get my car to pull past about 4000-4500 rpm but after converting to TBI, it easily pulls to the red line. Someday I'll do a dyno run just to see what's really happening.
In stock form I could never get my car to pull past about 4000-4500 rpm but after converting to TBI, it easily pulls to the red line. Someday I'll do a dyno run just to see what's really happening.
Hi guys - so looking at those dyno results it appears the stock cars all start loosing torque once you get over 4000 RPM.
That would seem to fit with the seat of the pants "now would be a good time to shift" feel that I get at 4000 RPM.... at least it appears my engine is normal. (not the owner of course, just the engine)
That would seem to fit with the seat of the pants "now would be a good time to shift" feel that I get at 4000 RPM.... at least it appears my engine is normal. (not the owner of course, just the engine)
TR3driver
Great Pumpkin - R.I.P
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I don't own a TR6, but I'm starting to understand better why everyone want to modify them!
The "seat of your pants" responds to power, not torque. With rated peak power at 4500 (up to 72) or 4900 (73 on); it shouldn't be feeling out of breath until at least 500 rpm beyond the peak, and optimum shift point won't be until farther yet.
(If you listen to it, the seat of your pants is pretty good at picking nearly optimum shift point ... you should feel the same acceleration after the shift as before it.)
Most common cause of "shortness of breath" in my experience (with earlier TRs and other cars) is tired valve springs allowing the valves to float. Camshaft wear is common too, but has less of an effect.
The "seat of your pants" responds to power, not torque. With rated peak power at 4500 (up to 72) or 4900 (73 on); it shouldn't be feeling out of breath until at least 500 rpm beyond the peak, and optimum shift point won't be until farther yet.
(If you listen to it, the seat of your pants is pretty good at picking nearly optimum shift point ... you should feel the same acceleration after the shift as before it.)
Most common cause of "shortness of breath" in my experience (with earlier TRs and other cars) is tired valve springs allowing the valves to float. Camshaft wear is common too, but has less of an effect.
The engine in my 6 is slightly modified with the usual stuff and seems to pull nicely up to at least 4800 RPM. Most of my shifting is done in the 3500 to 3800 range though. No need to beat on the car to much. Even if I did have 150hp which I don't the car could still not keep up with most modern cars with 200hp and more. But it's still much more fun to drive than most newer cars.
TR3driver
Great Pumpkin - R.I.P
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Which may or may not actually mean anything ... stock TR4A advance curve stops @ 2400 rpm (40795 dizzy) but it didn't even reach peak torque until 3000.poolboy said:
The engine in my TR3A when it got wrecked was close to totally stock except for 87mm liners. Still had the original well-worn camshaft, etc. It would pull hard to well over factory red-line in lower gears, and given enough time (love those desert highways) pull about 4700 in 4th OD.
Brosky
Great Pumpkin
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If you look at the printout of the dyno runs on mine, you will see, that with all of the mods, the true power drop off is at 5,200rpms. It will climb well beyond that, but that is the peak power shifting point.
Brosky 2010 Dyno Runs
We did run it up to almost 6,000rpms just to see if the HP and Torque would climb, but as the cam advertises, the peak range is 2,000-5,200rpms.
I did send these to Jeff for verification and the distributor that I have works very well with everything else. He curved it based on the other mods and the cam info that I sent to him when the engine was being built.
And 5,800rpms in 4th gear equates to 120mph on the speedometer.
This will also help to show that there is really no magic 150HP cam.
Brosky 2010 Dyno Runs
We did run it up to almost 6,000rpms just to see if the HP and Torque would climb, but as the cam advertises, the peak range is 2,000-5,200rpms.
I did send these to Jeff for verification and the distributor that I have works very well with everything else. He curved it based on the other mods and the cam info that I sent to him when the engine was being built.
And 5,800rpms in 4th gear equates to 120mph on the speedometer.
This will also help to show that there is really no magic 150HP cam.
poolboy
Yoda
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Brad Baumgart has dyno results for a stock engine, Tom. I'm pretty sure it hardly compares to some of these souped up engines though.tdskip said:
https://www.6-pack.org/sixpack//index.php?option=com_content&task=view&id=379&Itemid=2
Thanks guys.
Randall - maybe you have a spare TR4 motor I can use as an upgrade in the TR6 :laugh:
So I went out, and in the name of science of course, did some more checking and which mainly consisted of driving like hooligan*;
1) confirmed that she'll pull past 5000 RPM without issue but it doesn't <span style="font-style: italic">feel</span> like I am gaining anything by doing so. Doing so mainly produces extra noise....
2) Best acceleration <span style="font-style: italic">seems</span> to occur when shifting at 4000 RPM
3) If you really get on her and shift at 4000 RPM you'll be going well over the speed limit pretty darn quickly
4) #3 was really pleasing since it helped me realize that while she doesn't like rev like an Alfa, she still hauls the mail
*safe road conditions were used
Randall - maybe you have a spare TR4 motor I can use as an upgrade in the TR6 :laugh:
So I went out, and in the name of science of course, did some more checking and which mainly consisted of driving like hooligan*;
1) confirmed that she'll pull past 5000 RPM without issue but it doesn't <span style="font-style: italic">feel</span> like I am gaining anything by doing so. Doing so mainly produces extra noise....
2) Best acceleration <span style="font-style: italic">seems</span> to occur when shifting at 4000 RPM
3) If you really get on her and shift at 4000 RPM you'll be going well over the speed limit pretty darn quickly
4) #3 was really pleasing since it helped me realize that while she doesn't like rev like an Alfa, she still hauls the mail
*safe road conditions were used
TR3driver
Great Pumpkin - R.I.P
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There probably is some correlation (usually) between maximum advance and peak torque; since both torque and advance depend to some extent on volumetric efficiency. But peak power is normally well beyond peak torque.poolboy said:
And after all, power is what it takes to accelerate.
There is an interesting (if rather general) discussion at https://www.jcna.com/library/tech/tech0013.html of what affects the optimum advance curve.
And just for kicks (and because I've got it handy), here are the published torque & power curves for a stock Stag. BTW, it's advance curve continues out to 6400 rpm, beyond even peak power.
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poolboy
Yoda
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https://www.jcna.com/library/tech/tech0013.html
Mind numbing, Randall.
Mind numbing, Randall.